STP® Oil Treatment for Gearboxes is a mineral oil-based additive designed to lubricate hard-to-reach areas including gearboxes, transmissions, differentials, back axles, and steering boxes. In one easy application, it allows for smoother gear changes. This treatment reduces friction and noise, minimizes gearbox wear and corrosion, and removes harmful acids and deposits. It is suitable for use in manual gearboxes, differentials, back axles, and steering boxes. However, it is not recommended for use in automatic gearboxes, overdrives, or slip differential axles. The product comes in a 150ml size.